import java.util.ArrayList;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: Admin
 * Date: 2022-04-29
 * Time: 11:12
 */
abstract class Student {
    abstract void fun();
}

class Animal extends Student{

    void fun() {
        System.out.println("Animal");
    }
}

class Duck extends Animal{
    void fun() {
        System.out.println("Duck");
    }
}
public class TestDemo {
    public static void main(String[] args) {
        Student student = new Duck();
        student.fun();
    }
    public static void main1(String[] args) {
        Integer a = 128;
        Integer b = 128;
        System.out.println(a ==b);
    }
}